The present invention relates to dual-mode phones which support both Wi-Fi and Cellular connections.
Dual-mode phones, which support calls over Wi-Fi or Cellular connections are becoming more popular. With a good supporting infrastructure, users can initiate calls in one system, such as cellular, and transition to the other system, Wi-Fi, when in range of a supporting Wi-Fi system. Users can also transition from one Wi-Fi access point (AP) to another Wi-Fi AP.
But supporting voice over Wi-Fi systems is a challenge. To maintain a high Quality of Service (QoS) on voice calls, a stringent set of bandwidth, delay, jitter, and packet loss metrics must be continuously met.
As a network becomes more loaded with all types of traffic, QoS on voice calls will degrade. This degradation may occur on one AP in a network, with other nearby APs having capacity.
What is needed is a way to trigger the handover of voice calls to alternate networks when QoS degrades.